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Haemodynamic long-term effects of metoprolol at rest and during exercise in essential hypertension
Insights
Metoprolol effectively lowers blood pressure and heart rate in patients with essential hypertension over one year. Long-term use of this beta-blocker did not show significant side effects or less cardiac output depression compared to similar drugs.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Essential hypertension is a common cardiovascular condition.
- Beta-adrenoceptor blockers are a standard treatment for hypertension.
- Metoprolol is a new beta-adrenoceptor blocker whose long-term hemodynamic effects require evaluation.
Purpose of the Study:
- To evaluate the long-term hemodynamic effects of metoprolol in patients with WHO stage I essential hypertension.
- To assess the impact of metoprolol on blood pressure, heart rate, cardiac output, and peripheral resistance.
- To compare the hemodynamic effects of metoprolol with other beta-adrenoceptor blockers.
Main Methods:
- A one-year outpatient study involving twelve men with untreated essential hypertension.
- Hemodynamic parameters including oxygen consumption, heart rate, cardiac output, and intraarterial blood pressure were recorded at rest and during exercise.
- Subjects were treated with metoprolol (50-250 mg/day) as monotherapy.
Main Results:
- Metoprolol reduced mean arterial blood pressure by approximately 12% at rest and 9% during exercise.
- Heart rate decreased by about 22% at rest and 20% during exercise.
- Cardiac index was reduced by approximately 22% at rest and 17% during exercise, with no significant compensatory increase in stroke volume or decrease in total peripheral resistance. No side effects were observed.
Conclusions:
- Metoprolol demonstrates significant long-term reductions in blood pressure and heart rate in patients with mild to moderate essential hypertension.
- The hemodynamic effects of metoprolol are comparable to other beta-adrenoceptor blockers.
- The study did not support the hypothesis that metoprolol causes less cardiac output depression than other beta-blockers.
Abstract:
1 Twelve men with untreated essential hypertension in WHO stage I were studied on an outpatient basis to evaluate the haemodynamic long-term effect of a new beta-adrenoceptor blocker, metoprolol. 2 Oxygen consumption, heart rate, cardiac output (Cardiogreen) and intraarterial brachial pressure were recorded at rest in a supine and sitting position and during steady state work at 300, 600 and 900 kpm/min. 3 The subjects were treated with metoprolol (dose 50-250 mg/day) as the sole drug for 1 year and the haemodynamic study was repeated. 4 Mean arterial blood pressure was reduced about 12% at rest and 9% during exercise. The heart rate was decreased about 22% at rest and 20% during exercise. There was no significant compensatory increase in the stroke volume and consequently the cardiac index was reduced about 22% at rest sitting and about 17% during exercise. There was no decrease in total peripheral resistance. 5 No side-effects were seen. 6 The major haemodynamic long-term effects of metoprolol in mild and moderate essential hypertension resemble those seen by other beta-adrenoceptor blockers like alprenolol, atenolol and timolol. The study has not given support to the assumption that metoprolol should cause less depression in cardiac output than other beta-adrenoceptor blockers.